Organoborane amine complexes are known. For example, organoborane amine complexes used for the bulk polymerization of acrylic monomers, are described in U.S. Pat. No. 3,275,611 (Sep. 27, 1966). Certain organoboron compounds such as trialkylboranes by themselves, however, are pyrophoric in the presence of oxygen, so preformed complexes between the organoboron compounds and amine compounds are required to have the benefit of imparting improved stability to organoboron compounds such as the trialkylboranes.
Recent modifications on the structure of organoborane amine complexes are also described in U.S. Pat. No. 6,706,831 (Mar. 16, 2004), and their use in acrylate based adhesives. The combination of alkylborane amine complexes with amine reactive decomplexing agents to initiate the polymerization of acrylic adhesives at room temperature, is also described in the '831 patent. Such compositions offer the advantage of rapid cure and adhesion to low energy surfaces.
This invention differs distinctly from the prior art of organoborane amine complexes in that it relates to a new use of organoborane amine based complexes used in an ink system for generating precise patterns of polymers or polymer composites on surfaces at low temperatures including room temperature and below. In this case, the ink system is defined as the medium or media used to generate a polymeric pattern, and is not limited to the common applications associated with non-reactive pigmented inks, such as those found in ballpoint pens. The ink system herein typically contains an ink and a developing medium. As used herein, the ink, as distinguished from the ink system, is defined as one or more components of the ink system that is transferred to the surface in the image of the pattern. The developing medium is the medium to which the ink is exposed to develop the pattern. The process of developing the pattern is defined as a process in which the pattern placed on the surface undergoes a net increase in number average molecular weight by polymerization and/or crosslinking. The ink system is differentiated from common inks in that it is reactive, and can be rapidly developed in ambient conditions. While the method described herein can be used to mark characters or patterns, as an alternative to writing, stamping, or labeling, on solid surfaces such as plastics, ceramics, glasses, metals, paper, or wood, it is also useful for creation of patterns with finer scale features such as those currently created by lithographic processes for microelectronics.
For example, most current microlithographic methods employ ultraviolet (UV), electron-beam (e-beam), ion beam, or x-ray irradiation to develop the pattern. These methods have limitations for developing in depth or in shadowed regions, and also require the presence of the appropriate radiation source and associated process infrastructure which can be quite costly. Other non-photochemical methods typically require heat to develop the pattern. In addition to being a mild, rapid, and robust ambient process, the method herein features the key advantage of working with a wide variety of surfaces. Further, the method herein uses an ink system that is shelf stable yet allows patterns to be developed rapidly under ambient conditions.
The invention utilizes alkylborane chemistry to present a unique, facile, and low cost method of developing patterns onto surfaces including low energy plastics, in ambient conditions, without the need for a radiation source such as UV or e-beam. The method allows a wide range of polymers and polymer composites to be created in images or topological patterns on various surfaces, for controlling properties such as surface texture, appearance, adhesion, release, paintability, cell adhesion, friction, protein adsorption, pH response, reactivity, and conductivity for electron, ion, photon, or phonon transport. The method is useful in applications including macroscopic printing or labeling, printing of electronic and other conductive circuits, and microlithography or nanolithography for electronics, such as fabrication of semiconductors, organic electronics and displays such as transistors and light emitting diodes, biological engineering such as tissue scaffolds, biological testing, microfluidics, catalysis and bio-catalysis, and imprinting of patterns or text onto various surfaces for security and loss prevention such as radio frequency identification tags. The method can alternatively be used to create templates for subsequent use in such applications.